400-V Amorphous IGZO Thin-Film Transistors With Drift Region Doped by Hydrogen

The 400-V amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) with the drift region doped by hydrogen near the drain side are demonstrated in this work. The breakdown voltage ( {V}_{\text {BD}} ) increases with the length of the drift region ( {L}_{\text {drift}} ), and the maximum {V}_{\text {BD}} of 406 V is achieved at the {L}_{\text {drift}} of 5~\mu \text{m} for the a-IGZO TFT. The drift region endures the high-operating voltage to enhance the {V}_{\text {BD}} , determined by the emission microscope (EMMI) detection and simulation. The output current of the high-voltage (HV) device with the drift region increases with the increasing doping-hydrogen flow rate. The X-ray photoelectron spectroscopy (XPS) proves that the doped-hydrogen improves the carrier concentration in the a-IGZO film. Therefore, the hydrogen doping region takes a low proportion of the whole ON-resistance ( {R}_{ \mathrm{\scriptscriptstyle ON}} ). The proposed 400-V a-IGZO TFTs exhibit the excellent {R}_{ \mathrm{\scriptscriptstyle ON}} versus {V}_{\text {BD}} tradeoff relationship. The HV device with a drift region doped by hydrogen exhibits a negative shift of the threshold voltage ( {V}_{\text {th}} ) under the high bias stress (at {V}_{d} =100 V and {V}_{g} =5 V) because of the channel hot-carrier effect.